1. (Field of the Invention)
The present invention generally relates to a disc cartridge of a generally rectangular configuration for removably accommodating a disc-shaped recording medium such as, for example, an optical recording disc or a magnetooptical recording disc and, more particularly, to a lid structure for the disc cartridge for selectively opening and closing the access opening leading into the interior of the disc cartridge for removal or replacement of the disc-shaped recording medium.
2. (Description of the Prior Art)
The disc cartridge of the type referred to above is disclosed in, for example, the Japanese Laid-open Patent Publication No. 5-243626, published in 1994. According to this publication, the disc cartridge comprises a generally rectangular flattened casing having an access opening defined at a rear end thereof so as to extend over the entire width thereof. This known disc cartridge also includes a lid connected to the casing for selective pivotal movement between opened and closed positions to allow the disc-shaped recording medium, for example, the optical disc, to be removed from and inserted into the interior of the casing, respectively, through the access opening. The opposite end of the lid is formed with an elastic arm having an engagement pawl formed at one end thereof, which pawl is engageable in an engagement hole defined in the casing to cause the lid to close the access opening. Release of the engagement pawl from the engagement hole to open the access opening can be accomplished by inserting a pressure applying tool such as, for example, a pin into the engagement hole to allow the elastic arm to yield.
The capability of the lid being selectively opened and closed is necessitated to allow an "encased" optical disc, that is purchased, for example, in the form as accommodated within the disc casing, to be replaced with a different, "uncased" optical disc that is separately purchased without the disc casing. As is well known to those skilled in the art, certain optical disc recording and/or reproducing devices (players) require the use of a dedicated disc casing and, on the other hand, not only can optical discs for use therewith be available in the form as encased within such a dedicated disc casing, but they are also available in the form as uncased, that is, without the dedicated disc casing. If the "encased" optical disc has audio and/or video information such as, for example, music and/or computer application software, recorded thereon, the capability of the lid being selectively opened and closed in the dedicated disc casing makes it possible for the user to replace the encased optical disc with an "uncased" blank optical disc so that the user can record audio and/or video information on such blank optical disc on his or her own or at his or her will.
The capability of the lid being selectively opened and closed in the prior art disc cartridge often poses a problem. As described above, the lid employed in the prior art disc cartridge is of a type wherein the elastic arm is elastically deformed or yielded to allow the engagement pawl to disengage from the engagement hole, and this structure makes it difficult to ascertain if the optical disc within the disc cartridge has been replaced with another one once the disc cartridge containing the optical disc has been inserted into the player which may be of a type built in, for example, a computer.